ISO 3960:2017

Overview - ISO 3960:2017 (Peroxide value, iodometric visual endpoint)

ISO 3960:2017 specifies an iodometric (visual) method to determine the peroxide value (PV) of animal and vegetable fats and oils. The peroxide value quantifies oxygen chemically bound as peroxides (mainly hydroperoxides) and is expressed in milliequivalents (meq) of active oxygen per kilogram. The method covers fats, oils, fatty acids and their mixtures with PVs from 0 to 30 meq/kg, and is applicable to margarines and fat spreads with varying water content. Milk fats and lecithins are excluded.

Key topics and technical requirements

• Principle: Peroxides liberate iodine from potassium iodide in an acidic isooctane/acetic acid medium; liberated iodine is titrated with sodium thiosulfate using a starch indicator for a visual endpoint.
• Scope limits: Applicable range 0–30 meq O2/kg; not suitable for milk fats (see ISO 3976) or lecithins.
• Sample mass: The method fixes sample mass (5 g for PV > 1 meq/kg; 10 g for PV ≤ 1 meq/kg) because PV results are sample-mass dependent and dynamic (dependent on sample history).
• Reagents & apparatus: Requires degassed isooctane, glacial acetic acid, potassium iodide, standardized sodium thiosulfate (0.01 N prepared daily or titre determined), starch indicator, burette or automatic titrator, pipettes, analytical balance, Erlenmeyer flasks.
• Procedure highlights: Prepare and standardize sodium thiosulfate; dissolve sample in isooctane/acetic acid; add KI; allow reaction; titrate to visual endpoint with starch.
• Quality/precision: Includes precision data from interlaboratory testing and instructions for reporting results.

Applications and who uses this standard

• Food industry quality control: edible oil and fat producers monitoring oxidation and shelf life.
• Laboratories: contract analytical and official control laboratories performing routine PV assays.
• Procurement and compliance: buyers, receivers and regulators specifying permissible PV limits in contracts and legislation (Codex references).
• R&D and stability testing: formulation and shelf-life studies for margarines, spreads, and edible fats. The standard is widely used for routine peroxide measurement where a visual iodometric endpoint is acceptable and provides a consistent, internationally recognized protocol.

Related standards

• ISO 3976 - preferred iodometric PV method for milk fats (excluded from ISO 3960).
• ISO 27107 - potentiometric determination of peroxide value.
• ISO 661 - preparation of test sample for fats and oils.
• ISO 5555 - recommended sampling methods.

Keywords: ISO 3960:2017, peroxide value, PV determination, iodometric visual endpoint, animal and vegetable fats and oils, edible oils quality control.